Lamps of this type are known, for example, from West German Model Registrations No. 90-00,959 and No. 90-13,783. They consist essentially of a transparent housing or lamp tube, into which a bulb, such as a florescent bulb, is inserted possibly with a reflector and an anti-glare grid. The lamp tube is sealed tightly at both ends with caps. The problem with these lamps is the difficulty of replacing the bulb.
A design which simplifies bulb replacement has already been proposed in West German Utility Model Registration No. 90-13,783. This design offers the advantage that the cap can be sealed with a knob that turns by hand.